Can we actually update/upgrade Pega personal edition environment instead of always downloading the entire product to work. I even feel there should be an exercise which can help the interested pega architects to learn the concepts of upgrade.
Personal Editions are not meant to be upgraded. You need to package your code, download and install a new PE, reinstall your code on the new PE, then make changes such as specifying the latest version of UI-Kit.
If you have overridden UI-Kit rules you will not be able to see what changes have been made. It is also possible that security roles and privileges have been added. It helps to maintain a copy of the original PE for comparison purposes.